BNAMEb
   BBCBasic on different host machines

BDESCRIPTIONb
   BBCBasic has been implemented on many machines, and it is often useful
   to find out exactly what hardware a program is running on.  On all
   Acorn hardware, this is simple enough, as INKEY-256 and OSBYTE 0,1 give
   unique values for the machine you are using.  However, some machines do
   not implement negative INKEYs, and so would just wait about 12 minutes
   for you to press a key, and some do not let you do an OSBYTE call. 
   There are ways around this though.  In this discussion, the following
   Basics will be refered to:

    BBCBasic(2/4)	6502 Basic, as supplied in the B and Master
    BBCBasic(32)	32000 Basic, as supplied with the 32016 co-pro
    BBCBasic(V)	ARM Basic, as supplied in the Archimedes
    BBCBasic(Z80)	Z80 Basic, for Acorn CPM, Torch CPN, Tatung
			Einstein, Cambridge Z88, Amstrad Notepad, or
			modified for Tube with BBC I/O
    BBCBasic(86)	80x86 Basic, for PC machines
    BBCBasic(X)	C-coded Basic, for UNIX platforms

BBCBasic(2/4) and BBCBasic(V) could also be called BBCBasic(65) and
BBCBasic(ARM).  Some of the above can also be run on the Archimedes under
emulation.

Basic(65), Basic(32) and Basic(ARM) store the program in memory starting
from PAGE with a CR, and ending with xx, CR, &FF where xx is the last
character of the final line.  Basic(Z80) and Basic(86) store the program
ending with CR, 00, &FF, &FF.  Basic(65), Basic(32) and Basic(ARM) always
have access to the MOS and FILE calls and allow INKEY-256.  This allows us
to use ?(TOP-3)=0 to indicate Z80/86 or 65/32000/ARM, and to indicate
whether we can make a call to &FFxx or do INKEY-256.

OSBYTE 0,1 will return 6 indicating an Archimedes when running on an
emulator.  BBCBasic(ARM) running native always has PAGE>&8000.  This can
be used to indicate native.

Basic(86) starts with HIMEM>&FFFF, and BBCBasic(Z80) always has
HIMEM<&FFFF, so this check can be used to distinguish between Z80 and
80x86.  BBCBasic(86) allows only three MOS calls, OSBYTE 0,1 which returns
32, OSBYTE 135 to read the character at the cursor position and OSWORD 10
to read character definitions

Basic(Z80) may run under CPM or not under CPM.  All CPM calls go through a
jump vector at address &0005.  In some Basic(Z80) environments, the &0005
call returns zero to indicate non-CPM mode.  In other environments, there
isn't a jump vector there at all.  If we first test to see if there is a
jump vector there and if there is call it with C% set to 12 to ask for the
CPM version number, we can find out if we are running under CPM.  If the
call returns zero, then we are running in a non-CPM environment that
allows MOS and FILE calls.  If we are running in a non-CPM environment we
are probably running on a Cambridge Z88 or an NC100.  The Z88 has its
reset routine at location 0 starting with a &F3 byte.  This distinguishes
between Z88 and NC100, neither of which have any MOS or FILE calls.





B    REM Works on I/O,T6502,Arc,TZ80bbc,PC,CPM,Unix,NC,Z88,Einstein
    DEFFNOS_GetEnv:LOCAL A%,X%,Y%,A$
    cpm%=0:dos%=0:bbc%=0:os%=-1:arc%=0:unix%=0:z88%=0:nc%=0
    bbc%=?(TOP-3)<>0:IFNOTbbc%:dos%=HIMEM>&FFFF:
      IFNOTdos%:cpm%=?5=&C3:IFcpm%:C%=12:IFUSR5=0:bbc%=TRUE:cpm%=0
    IFbbc%ORdos%:A%=0:X%=1:os%=(USR&FFF4 AND&FF)DIV256
    IFNOTbbc%ANDNOTdos%ANDNOTcpm%:z88%=?0=&F3:nc%=NOTz88%:A$=$&A000
    arc%=(os%=6 AND PAGE>&8000):unix%=os%=8:IFos%=32:A$=$&100
    IFarc%:LOADATN"OS_GetEnv"TOA$:A$=MID$(A$,1+INSTR(A$," "))
    IFLENA$=0:IFbbc%:A$=$&600 ELSE IFLENA$=0:A$=$&3800
    A%=INSTR(A$+" "," "):run$=LEFT$(A$,A%-1):IFrun$<>"":=MID$(A$,A%+1)
    X%=ctrl%:Y%=X%DIV256:A%=9:?X%=0:X%!1=data%:!data%=0:CALL&FFD1:
      IF!data%AND?data%+data%?2<>8:data%?(1+?data%)=13:=$(data%+1)
    =""b

The above routine returns any command line parameters and sets the
following global variables: run$ is set to the command used to start the
program, os% contains the host operating system value (see below); cpm%,
dos%, bbc%, unix%, arc%, z88% and nc100% are flags indicating what
hardware is running.  These can be used to indicate the following:

os%	Host os value (see below)
run$	Pathname used to start the program
bbc%	Calls to &FFxx and INKEY-256 ok, names are :d.$.dirname.leafname
cpm%	Calls to &0005 allowed, filenames are d:filename.xtn
dos%	filenames are d:\dirname\filename.xtn
unix%	filenames are /dirname/filename
arc%	extended Basic functions allowed
nc%    running on an Amstrad NC100/150/200
z88%   running on a Sinclair Z88

Host OS values returned in os% include the following:

	-1 : Unknown		 6 : Archimedes/Acorn
	 0 : Electron		 7 : Springboard
	 1 : BBC		 8 : Unix
	 2 : BBC B+
	 3 : Master 128		30 : Amstrad CPC
	 4 : Master ET		31 : Spectrum
	 5 : Master Compact	32 : IBM-type PC